Summary of cotton seedling disease in Virginia.

Dr. Pat Phipps, Virginia Tech, 6321 Holland Rd., Suffolk, VA 23437, Phone (757) 657-6450 ext. 120 or 143, FAX (757) 657-9333, email

Causal Organisms: The most frequent cause of damping-off in cotton is Rhizoctonia solani, which is a common soil-inhabiting fungus. Occasionally, Pythium species are found causing damping-off disease in localized areas of fields.

2004 Season Overview and Research Activity: Yields of cotton in Virginia are expected to average 889 lb or 1.85 bales/A in 2004. Seedling diseases were widely distributed in cotton fields in 2004, but the overall impact was minimal since stands were generally uniform and showed excellent vigor. Weather conditions from mid-April until completion of planting in late May were favorable for rapid emergence and exceptional vigor of seedlings. Areas with poor stands in 2004 were often associated with soil compaction by heavy rainfall immediately after planting, saturated soil conditions, and/or placement of seed too deep. Monthly rainfall in May, June, July, August, September and October was 0.96, 0.84, 6.62, 5.23, 0.67, and 1.09 in. above normal in 2004. Rainfall during the period totaled 43.52 in., which was 15.4 in. above normal. During this period, the accumulation of DD60 heat units was 2191 which was near the 9-yr mean of 2169. All commercial seed in Virginia are treated with a mixture of three or more fungicides that offer the latest technology in chemistry for control of damping off. Field trials continue to show that these treatments generally provide good to excellent protection of seedlings. When planting in situations that pose a high risk of damping-off diseases, the application of Quadris 2.08F 0.6 fl oz + Ridomil Gold 0.12 fl oz/1000 ft of row has significantly improved seedling health and increased yield due to greater uniformity in plant populations.